The present invention relates to rolls in paper handling machines, such as slitters, which are driven only by the web and to the brakes for stopping the rotation of such rolls when the paper web breaks.
Paper is manufactured in widths of up to 300 inches or more and wound into machine rolls which may weigh over 120,000 lbs. The machine rolls are removed from the papermaking machine as they are formed. Further processing of the machine roll to create smaller rolls or individual sheets of paper is preformed by other machines. The machine roll can be processed by sending the web through a group of slitters which cut the web into a plurality of narrower webs typically through the use of rotating circular knives. Paper webs are processed at speeds of up to 10,000 feet per minute. As the paper travels from the unwind station to the winder station, it passes over idler rolls to guide the web as it is fed into the rotating knives of the slitter.
For simplicity, the idler rolls have no drive and are simply free turning on internal bearings. As the web is drawn over the idler rolls, the rolls rotate with the speed dictated by the speed of the paper. If the paper web breaks in the slitter, it is often necessary to manually clean out broke from the slitting machine. However, the rapidly turning idler rolls may continue to rotate at several thousand RPM for a relatively long period of time. Waiting for the idler rolls to stop turning would result in the loss of valuable production time if a mechanism were not available to bring the idler rolls to a rapid stop. In existing machines a wheel can be brought into engagement with the idler rolls. The wheel is connected by a clutch brake and brings the roll to a stop. However, such braking wheels are subject to wear and contact the exterior surface of the idler roll. What is needed is a low maintenance brake without moving parts or one in which braking forces are exerted on the interior of the roll.